Such cyclonic separators are known from Japanese patent No. 2017921, Russian patent No. 1768242, UK patent application No. 2035151 and PCT patent application WO 00/23757.
The known cyclonic fluid separators comprise a tubular throat portion in which the fluid stream is accelerated to a possibly supersonic speed and rapidly cooled down as a result of adiabatic expansion. The rapid cooling will cause condensation and/or solidification of condensables in the fluid stream into small droplets or particles. If the fluid stream is a natural gas stream emerging from a natural gas production well then the condensables may comprise water, hydrocarbon condensates, waxes and gas hydrates. These separators furthermore comprise an assembly of swirl imparting vanes in an inlet portion upstream of the throat portion, which vane or vanes are tilted or form a helix relative to a central axis of the throat portion to create a swirling motion of the fluid stream within the separator. The centrifugal forces exerted by the swirling motion on the fluid mixture will induce the relatively high density condensed and/or solidified condensables to swirl to the outer periphery of the interior of the throat portion and of a diverging outlet section whereas relatively low density gaseous components are concentrated near the central axis of the separator. The gaseous components are subsequently discharged from the separator through a primary central outlet conduit, whereas the condensates enriched fluid stream is discharged from the separator through a secondary outlet which is located at the outer circumference of the diverging outlet section.
A disadvantage of the known vortex generators in the inlet section of the separator is that the amount of rotation imposed on the fluid stream is limited, unless the blades of the vortex generator are oriented at a large angle relative to the central axis of the separator, in which case blades create a high flow restriction in the fluid stream.